Militants in the Sinai Peninsula fired a rocket at the Israeli resort city of Eilat today during the height of tourist season, in retaliation for an airstrike that killed four of their own last week.

A spate of militant activity out of the Sinai in recent weeks is prompting greater security cooperation between Israel and the Egyptian military, both of which are eager to contain the heightened threat.

Militants in the Sinai are feeling squeezed by Egyptian military efforts to subdue them in the vast desert peninsula that have been expanded since the ouster of former President Mohamed Morsi last month, The Christian Science Monitor reports. The region has many militant groups operating there.

“The Army for the longest time has been holding back from interfering in Sinai,” a high-ranking security official in northern Sinai told the Monitor. “The elements in this area fear that they might lose this [strategic area] now that we have deployed more tanks and we’re putting more effort into clearing this area, so obviously they are going to fight back.”

Israel and Egypt have upped their cooperation in recent weeks, with Israel granting approval for the Egyptian military to move two additional battalions into the Sinai, according to the Monitor. The peninsula is largely demilitarized as part of the 1979 Israel-Egypt peace treaty, but Egypt can deploy additional forces in the area with the OK from Israel

A Sinai-based Islamist militant group, Magles Shoura Al Mujahadeen, claimed responsibility for today’s attack, Reuters reports. It is not the same group that was targeted in last week’s strike.

"In a swift response to the latest crime of the Jews that killed 4 Mujahideen in the land of Sinai through a strike by a pilotless plane, the lions of Maglis Shoura al-Mujahideen ... were able to strike the occupied city of Om al-Rashash "Eilat" with a rocket," it said in a statement published online.

"We assure that neither Eilat nor any other Israeli cities will be blessed with security, tourism or economy," it added.

Iron Dome protects Israeli territory by firing interceptor missiles at rockets headed toward Israeli targets. Amos Harel, military correspondent for the Israeli newspaper Haaretz, told the Monitor last month that although Eilat is the closest big target to militants in the Sinai, its location – wedged between Jordan and Egypt at Israel’s southernmost tip – has made it difficult to defend with Iron Dome.